Make your audio applications stretchier than ever

Rubber Band Library is a high quality software library for audio
time-stretching and pitch-shifting. It permits you to change the
tempo and pitch of an audio stream or recording dynamically and
independently of one another.

New: Rubber Band Library v1.8.1 released (28th Oct, 2012)

Rubber Band Library is intended for use by developers creating
their own application programs rather than directly by end users,
although it does also include a simple (free) command-line utility
program that you can use for fixed adjustments to the speed and pitch
of existing audio files.